WO2024175866A1

WO2024175866A1 - Improvements in or relating to food processing

Info

Publication number: WO2024175866A1
Application number: PCT/GB2024/000008
Authority: WO
Inventors: Simon Surinder Pal Grewal
Original assignee: R Processing Limited
Priority date: 2023-02-22
Filing date: 2024-02-19
Publication date: 2024-08-29

Abstract

The Applicant has developed a method (and apparatus) for treating a raw meat eg. poultry, aged beef or fish product including drying the meat surface rapidly, using chilled, dry air, at 4°C (which gives a loss of between 8 to 10 percent in the weight of the meat), ensuring a shelf life of 14 days for fresh raw poultry. Embodiments of the method include extending the shelflife of some products to 50 days with a weight loss of 20%.

Description

IMPROVEMENTS IN OR RELATING TO FOOD PROCESSING

This invention relates to improvements in or relating to food processing and is more particularly concerned with an antimicrobial method of treatment of raw meat products and apparatus for implementing the method.

The present invention is concerned with the reduction, destruction, inhibition or control of microbial populations on raw meats. Of concern are all types of microbial populations, most particularly single cell organisms, such as bacteria, yeasts and moulds.

Microbial populations present in the processing and storage of fresh meat products may render the meat unsuitable or unsafe for consumption; yeasts, moulds and bacteria on the meat products need to be reduced to seemingly as low a level as possible, to prevent or reduce the possibility of the meat becoming spoiled, more particularly whilst in storage.

Many antimicrobial methods of treatment or processes of food products are known in the art:-

For example, chemical based antimicrobial treatments are available in which antimicrobial and bactericidal agents are used to kill microorganisms. However, disadvantageously, such chemical based treatments may be unsuitable for use in some applications, particularly with raw meats, as the antimicrobial chemicals themselves may be unsuitable for consumption. Additionally, such chemical treatments may simply spoil the product.

Antimicrobial process involving techniques of irradiation, for example ultraviolet radiation can be used. However, again disadvantageously, there is a danger of damage to the product itself particularly where the product is raw meat which has a distinctive colour and flavour vulnerable to ionising radiation.

Previously proposed antimicrobial processes aimed at extending the shelflife of raw meat products may be relatively complex and the subject of intensive research. Some examples of Patent Specifications, proposing such processes, all of which may have drawbacks, are US 2020/0315220, US5512309 and EP0659346.

Accordingly, it tends to be disadvantageous that, presently, without special treatment, raw meat (e.g. poultry) simply chilled and packaged retail ready for the consumer has a very limited shelf life (usually up to five days) and such special treatments tend to be unsatisfactory in some way and may not be successful.

Thus, the Applicant believes there is a need for a new, effective, preferably non-complex, antimicrobial method of treatment which can be used to reduce populations of microorganisms to as low a level as possible without damaging e.g. the delicate nutrients and volatiles in fresh raw meat products.

The Applicant is concerned with a process where the food spoilage bacteria, yeasts and moulds are rendered essentially dormant during the storage of fresh chilled meats.

The Applicant has previously developed method and apparatus for the antimicrobial treatment of articles including raw meat, as described in his previous patent specification No. GB2573842, the content of which is hereby referred to. Even so, the inventor believes, after some years of painstaking research and development, that he has invented a more satisfactory antimicrobial method of treatment of raw meat products and apparatus for implementing the method, in most instances leading to a far longer shelf life of the product.

It is an object of the present invention to provide an antimicrobial method of treatment of raw meat products which at least alleviates one or more of the aforementioned, or other, disadvantages of known methods and/or to provide apparatus for implementing such a method and/or to provide an antimicrobial method of treatment of raw meat products which is improved in at least some respect and/or which extends the shelf life of the product and/or apparatus for implementing such a method.

According to the present invention there is provided an antimicrobial method of treatment of a raw meat product comprising exposing the surface of the raw meat product rapidly to a high velocity flow of dry, chilled air sufficient to thereby dehydrate microorganisms on the raw meat to a low enough level of water activity to prevent or restrain metabolic and replicating activity of the microorganisms, to thereby extend the shelf life of the raw meat product beyond a 5 day period.

Typically, ‘ rapidly’ means a processing time of about 5 to 8 minutes to be maintained for the high velocity flow of dry chilled air causing the microorganisms also to rapidly dehydrate in this time to said low level. Bacteria are among the fastest reproducing organisms. In an ideal environment of suitable temperature, oxygen, food, pH, and water, they can double in number every 4 to 20 minutes.

Typically, ‘high velocity’ means a delivery speed of about 900 to 1300 litres of dry chilled air per minute.

Typically, ‘dry chilled air’ means air in a temperature range of about 2 to 4 degrees Celsius (for optimum quality) with a dew point in the range of about -15 to -70 degrees Celsius and preferably about -20 +/- 2 degrees Celsius.

Preferably, the antimicrobial method of treatment of the raw meat product comprises an initial step of exposing the surface of said product to blown air at ambient temperature and at ambient relative humidity in order to remove most or nearly all (e.g. 99 %) of the free moisture and meat juices on said surface (preferably for about 40 +/- 10 seconds) prior to exposing the surface of the raw meat product rapidly to a high velocity flow of dry, chilled air.

In some instances, the raw meat product may be agitated or tumbled whilst being exposed to the air at ambient temperature and/or whilst being exposed the high velocity flow of dry, chilled air in order to ensure that the entire meat surface receives treatment. A smaller meat product of for example 0.5 kg to 1kg would be suitable for agitation or tumbling whilst being treated but a larger piece of e.g. 1kg may suffer bruising during agitation/tumbling and so may simply be suspended during treatment. Usually, after the raw meat product has been subjected to the high velocity flow of dry, chilled air it is packed into waterproof packaging at a chilled temperature ready for cold storage.

Advantageously, embodiments of the antimicrobial method would appear to be non-complex, cost-effective, repeatable, and suitable for a production line.

In practice, it is envisaged that, usually, a plurality of raw meat products (for example cut poultry pieces or whole chickens or beef sides) will be treated substantially simultaneously or sequentially along a production line apparatus providing a sterile environment for the antimicrobial method of the present invention.

Therefore, further according to the present invention there is provided apparatus for carrying out the method as described in the statement of invention bridging pages 2 and 3 of this specification.

Any convenient means may be provided for supplying rapidly a high velocity flow of dry, chilled air in a timed manner.

Said apparatus may include any features necessary for carrying out any of the afore-described preferred methods of antimicrobial treatment.

Preferably, the apparatus includes means to deliver the high velocity flow of dry, chilled air in the form of ‘air knives’ which may be known per se and preferably suitably positioned on either side of a conveyor means of the apparatus, in use, feeding meat products sequentially past the air knives. Smaller meat products may be tumbled or agitated on conveyor means comprising a lower conveyor during treatment and/or larger meat products may be suspended from conveyor means comprising an overhead conveyor during treatment.

The apparatus preferably includes a (main) tunnel or enclosure in which meat products are sequentially conveyed therethrough whilst being subjected to the high velocity flow of dry, chilled air. Where the method includes an initial step of exposing the surface of said product to blown air at ambient temperature and at ambient relative humidity, the apparatus may also include means to deliver air at ambient temperature, preferably, in the form of a second arrangement of ‘air knives’ which may be known per se and preferably suitably positioned on either side of the conveyor means of the apparatus, feeding meat products sequentially past the second arrangement of air knives. Smaller meat products may be tumbled or agitated on the conveyor means comprising a lower conveyor during treatment and/or larger meat products may be suspended from the conveyor means comprising an overhead conveyor during treatment.

Accordingly, the apparatus may include an auxiliary tunnel or enclosure in which meat products are initially sequentially conveyed therethrough (prior to treatment in the main tunnel) whilst being subjected to the air at ambient temperature and humidity.

The apparatus, preferably, includes a packaging station for packing the meat products after they have been carried on the conveyor means subsequent to treatment with the high velocity flow of dry, chilled air.

The antimicrobial method of treatment may be suitable for the treatment of any meat product e.g. poultry or beef.

Further advantageous features of an antimicrobial method and apparatus in accordance with the present invention will be apparent from the following description.

Embodiments of an antimicrobial method of treatment of a meat product and apparatus for implementing the method will now be described, by way of example only.

The Applicant has realised that populations of microorganisms present on the surface of raw meat products can be reduced, controlled, inhibited from growing or substantially destroyed, by exposing them rapidly to a high flow of dry, chilled air. The dry, chilled air rapidly dehydrates the microorganisms to a low enough level of water activity, which prevents them from carrying out their metabolic and replicating activities. This process also dries out the moisture on the exposed surfaces of the meat products. A very thin layer on the surface of meat cells loses water. When water activity outside the bacterial cell becomes low enough, the cell cannot take up water. This creates an osmotic stress and the bacteria becomes dormant. Despite a plentiful supply of food and other necessary conditions such as Oxygen and a suitable pH, the bacteria cannot reproduce or produce toxins. However, the natural enzymes of the meat do continue to work at very reduced rates at the low temperature, i.e. below 4°c. Under these conditions, raw poultry meat can last 14 days instead of the usual 5 days.

Each species of bacteria has a specific level of water activity at which it will become dormant. It will not reproduce, nor produce toxins or cause infection.

Pathogenic bacterial growth is not supported at water activity of 0.85 or less. Organisms like yeasts and moulds can withstand very low levels of water activity; their levels of water activity cut off is between 0.85 to 0.61 Aw

The Applicant has conducted experiments as later described herein and has established that drying the meat surface rapidly, using chilled, dry air, at 4°c (which gives a loss of between 8 to 10 percent in the weight of the meat), ensures a shelf life of 14 days for fresh raw poultry.

As will be appreciated, the advantages of extending the shelflife of fresh poultry from 5 to 14 days should be of great importance to the meat processing company. During specific holiday periods in the year, e.g. at Christmas, New Year and Easter, such companies are under stress to produce sufficient meat products to satisfy the extra demand over the holiday periods. By the present invention, the meat processing company can utilise a rapid chilled dehydration process, to build up large quantities of meats, ideally without suffering any wastage. Advantageously, this may also enable the meat processing company to market their fresh meat to more distant locations.

For the retail customer, there are also additional advantages besides the longer shelf life of the raw meat. When poultry meat has undergone treatment via the antimicrobial method of treatment of the present invention and is cooked, it cooks in a shorter time and may use 10 percent less energy during cooking; the roasted meat with skin has a crisp texture, which most cooks desire. According to figures from the UK meat industry, annual food wastage in the UK is around 300,000 tons, equivalent to 1 million cattle, 4.4 million pigs and 165 million chickens. In other countries the figures of wastage is equally apparent. Extending the shelf life using the antimicrobial method of treatment of the present invention of fresh meat should reduce these figures dramatically.

The rapid chilled dehydration process can be applied to all meats. Examples have been given for poultry, but the basic process should be applicable to other meats.

Experiments have been carried out by the Applicant on poultry meats of varying sizes classified into ‘smaller’ and ‘larger’ pieces. Pieces of poultry in a weight range of between about 0.5 and 1kg were considered ‘smaller’ and pieces larger than about 1kg were considered as larger. The experiments involved surface treatment of the poultry pieces using air under varying conditions and for varying periods of time.

One embodiment of apparatus (not shown) suitable for treatment of smaller meat pieces in accordance with the present invention was set up or arranged (from known components) to treat the meat pieces in a closed sterile environment, as follows:-

1. A main treatment tunnel or enclosure (food grade) was provided to create sterile conditions for meat pieces to be conveyed therethrough sequentially past a series of high velocity air knives located on either side of conveyor means in the form of a conveyor belt consisting of stainless steel mesh (food grade). The conveyor belt is provided with a control mechanism to regulate the speed of the belt.

2. Means was provided to agitate or tumble the meat pieces whilst on the conveyor belt (e.g. by vibrating the belt).

3. Means (dry air generator/s) was/were provided to feed filtered, dry, chilled air to the air knives for delivery on to the exposed surface of meat pieces being tumbled on the conveyor belt in the main treatment tunnel/enclosure.

4. An initial, short, auxiliary treatment tunnel or enclosure (food grade) similar to the main treatment tunnel/enclosure was provided to create sterile conditions for meat pieces to be conveyed therethrough on the conveyor belt sequentially past a series of high velocity air knives also located on either side of conveyor belt. Said auxiliary treatment tunnel or enclosure was positioned before the main treatment tunnel/ enclosure to allow for an initial treatment of the meat pieces prior to main treatment in the main treatment tunnel/enclosure.

5. A packaging station having filtered air at a chilled temperature was provided for meat pieces carried on the conveyor belt, after main treatment, to be received from the main treatment tunnel/enclosure under sterile conditions for packing into waterproof packaging.

6. The air knives and dry air generators had controls to regulate speeds, volumes of air per minute and means was provided to deliver chilled air where needed at pre-settable low temperatures.

7. The air knives used were of a type known per se produced by Solv Air and Spraying systems Ltd ( based in Farnham, Surrey). .

Experiments were carried out using the above apparatus as follows:-

1. Initially, filtered air at ambient temperature and at ambient humidity was blown through the air knives onto the exposed surfaces of smaller raw poultry pieces conveyed and tumbled on the conveyor belt whilst passing through the auxiliary treatment tunnel/enclosure. The purpose of this initial treatment was to dehydrate the meat pieces by blowing off as much moisture and meat juices as conveniently possible (say 99% of all moisture). The treatment time in the auxiliary treatment tunnel/enclosure was about 40+/- 5 seconds. The treatment is economical and has a low carbon footprint.

2. After treatment in the auxiliary treatment tunnel/enclosure, the poultry pieces were carried on the conveyor belt to the main treatment tunnel/enclosure to be treated (whilst being tumbled) by air knives blowing high velocity, dry filtered air at a temperature of about 2 to 4 degrees Celsius and at a dew point of -20 to -70 degrees Celsius for about 5 to 7 minutes. The dry air dehydrates the surfaces of the meat products rapidly. Accordingly, advantageously, the thin surface of the meat products is dried with all the encrusting bacteria (being extremely small - 1 to 2 microns in diameter and 5 to 10 microns long) having dehydrated completely. The bacteria and all other fungi are now in a dormant stage and cannot function.

3. After treatment in the main treatment tunnel/enclosure, the poultry pieces were carried on the conveyor belt to the packaging station into which filtered and chilled air was blown while the meat was packed into waterproof packaging. The packaging usually consists of retail trays under a waterproof lidding film and the packages are then kept in a cold chain of storage and delivery. The poultry pieces do need to be packed after the dehydration process in order to keep the meat from re-hydrating and retail ready.

The exceptional results of the above 3 stage experiments within the limits of the described operational parameters were as follows

An extended shelf life of the smaller poultry piece products from about 5 days to 14 days.

Other experiments were conducted with operating parameters outside of those as afore- described which yielded unsatisfactory results, For example, in the main treatment tunnel/enclosure if lower velocities of air were used than the 900 to 1300 litres of dry air per minute provided by the air knives more time was needed to dehydrate the bacteria of the poultry pieces e.g.substantially 20 minutes as compared to about 7/8 minutes. This allowed the bacterial load to increase before the low limiting water activity point was reached. Thus, 20 minutes processing time could not be considered as ‘sufficiently rapid’ within the context of that experimental process. Using operating temperatures in excess of 4 degrees Celsius tended to increase the bacterial load resulting in a shorter shelf life. Processing at a temperature of 4 degrees Celsius or below yielded a 14 day shelf life. With temperatures above 4 degrees Celsius the shelf life was only 5 days.

It is to be noted that with raw meat products when cut into portions, the cut tissue releases the contents of the cells; these are water soluble proteins e.g. Myosin, Actin, Tropomyosin, Troponin being the major contents, most favourable for replication. The Applicant has found that in deploying the rapid, dry, chilled air dehydration of surface bacteria on raw meat, the process time needs to be about 5 to 8 minutes to stop replication. Indeed, it has been found that the size or weight of the raw meat product does have an impact on the required treatment time with the dry chilled air. Smaller pieces of meat product require a longer treatment time than larger pieces. Smaller pieces can require a treatment time of about 8 minutes whereas larger meat products can require a shorter treatment time of about only 5 minutes. Accordingly, experiments were conducted on larger raw poultry products using a similar apparatus to that used for smaller raw poultry pieces.

A modified embodiment of apparatus (not shown) suitable for the antibacterial treatment of larger raw poultry pieces in accordance with the present invention has an overhead conveyor means from which the larger poultry pieces can be suspended (instead of being tumbled on a lower conveyor belt - which could cause bruising) whilst being treated in both the initial treatment tunnel/enclosure and in the main treatment tunnel/enclosure.

Smaller pieces of cut meat have a larger surface area compared e.g. to large sides of beef. Consequently, it was found that treatment time for larger meat products may only need to be about 5 minutes with about 40 +Z-5 seconds in the auxiliary treatment tunnel/enclosure.

It is to be appreciated that the known food process for raw meat that lasts for 5 days is simply to pack the chilled meat in waterproof fdm without the surface having been dried at all, thereby allowing growth of populations microorganisms so that the meat spoils after this time span.

Accordingly, it is believed that, advantageously, embodiments of the present invention provide for an extended shelf life of a raw meat product beyond the usual 5 days, in most cases up to about 14 days, utilising a non-complex method and a unique combination of known apparatus.

One embodiment of the present invention may include an optional step to the final stage of poultry packaging. This step involves the misting/treatment of poultry with (high quality) vegetable oil or the like/similar. Advantageously, this step improves the colouration of the meat (i.e poultry skin) and should stop any further loss of moisture from the poultry and thus stop any water condensing in the packaging on the meat .Advantageously, this step also means that the traditional use of carbon dioxide gas is not required during the retail packaging stage. This would cut production costs significantly.

The Applicant has realised that embodiments of the antimicrobial method of treatment generally as herein described may also be applicable/adapted to a variety of food (more particularly raw) products e.g in particular aged meat such as beef or ham, or fish such as salmon. For aged beef, the current known process used is to hang large cuts of prime meat in chilled conditions at a relative humidity of about 70% for at least 30 days. During this process, a thick crust of bacteria, fungi and moulds grow on the surface of the raw meat as the water activity is not controlled. At the end of the ageing period the heavily infested encrusted parts of meat are trimmed off. Thus, it tends to be disadvantageous that there is a loss of about 25-40% of the original weight of the beef due to the trimming. Such extensive trimming would not be needed in the Applicant method which avoids the growth of such bacteria etc. For hams, the meat is heavily salted and hung in cool conditions at a relative humidity of 70% for several months ; the meat becomes salty and loses about 30% of the body weight. Advantageously, using or adapting embodiments of the antimicrobial method of treatment generally as herein described, for aged beef or ham, initially and throughout the method, the outer surfaces of beef/ham would not support the formation of moulds and bacterial growth, thereby reducing a very significant wastage of beef/ham in the end product.

Currently, smoked salmon is high in sodium, as salt is used in its preparation. A 100 g serving of smoked salmon contains 672 mg of sodium chloride. A similar amount of fresh salmon has only 75 mg of sodium chloride.. As known, consuming too much sodium is detrimental to health; it raises the risk of stroke and heart disease. Embodiments of the antimicrobial method as herein described can be used/adapted for preparing healthy smoked salmon, without using too much salt. Presently, 120 g to 200 g of salt is used for each 1 kg of salmon to be cured. The Applicant method should be able to reduce this to a few grams. Also, the current known process is very polluting, resulting in 200 g of salt per kg of fish ending up in the waste water. The Applicant method should avoid such drawbacks.

In the Applicant method applied to fish, the salmon may be dehydrated in a gentle stream of air at a dew point of about -30 degrees and at a temperature of about 4 degrees centigrade for about 10 minutes. Then, the salmon may be allowed to rest under the same conditions for about 3 hours. After this, the above action may repeated 4 times. At the end of this method the salmon should have lost about 10% of its body weight. The salmon may then be misted with a dilute solution of sodium chloride and allowed to rest for several hours. This allows a pellicle of salt and protein to form on the surface of the salmon. This sticky pellicle allows smoke and wood flavonoids from the smoker used in the smoking process to adhere and infuse into the salmon. After this procedure, the salmon may be smoked for about 12 hours at a temp below about 27 degrees centigrade. Advantageously, the total loss of moisture from fresh salmon to smoked salmon may only be about 20%.

It is to be understood that the scope of the present invention is not to be unduly limited by the particular choice of terminology and that a specific term may be replaced or supplemented by an equivalent or generic term. Comprising’ may be replaced by ‘having’ or ‘including’; ,air‘ may be replaced by ,gas‘ or particular mixtures of gasses; rapidly¹ may be replaced by ‘rapid processing time¹, , method¹ may be replaced by , process¹. Further it is to be understood that individual features, method or functions relating to the antimicrobiological treatment or apparatus might be patentably inventive. The singular may include the plural and vice versa.

Additionally, any range mentioned herein for any parameter or variable shall be taken to include a disclosure of any derivable sub-range within that range or of any particular value of the variable or parameter arranged within, or at an end of, the range or sub-range or even outside said range or sub-range if this still achieves the the intended result of the present invention or improved result..

As used herein, the terms about¹, substantially¹, ,high velocity¹, , rapid¹, ,dry‘, chilled¹, sufficient¹, and similar relative terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this patent specification pertains; , rapidly¹ could be replaced by , quickly¹ or the like. It should be understood by those skilled in the art that these terms are intended to allow a description of certain features described and/or claimed without unecessarily restricting the scope of those features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations to the subject matter described and/or claimed are considered to be within the scope of the present invention.

The Applicant has made further important developments to the antimicrobial methods of treatment as herein described.

The Applicant has progressed the present invention as herein described by further increasing the shelf life of fresh, raw poultry and other meats from 15 days to over 50 days. The further developed antimicrobial methods of the present invention use ‘hurdle’ technology of low water activity and a low temperature of -3°C, without freezing meat, to achieve inactivation of meat and bacterial enzymes, to extend shelf life. ‘Hurdle’ technology means combining various bacteria-killing or bacteria inhibiting factors (e,g, water activity) to achieve a safe product with acceptable shelflife and an acceptable taste and consistency.

The Applicant achieves the remarkable increase in shelf life from 15 to over 50 days by modifying the methods as herein described to dehydrate the meat by 20% instead of 8 to 10 % as previously mentioned herein or 10 to 12% that the Applicant previously used, which only resulted in 15 days shelf life. Such additional dehydration further increases the concentration of soluble proteins in the meat. When this meat is exposed to a temperature of -3 °C, the meat does not freeze, as the freezing point of water in the meat is depressed. A higher concentration of soluble proteins results in lower freezing points of water in the meat. At this lower temperature below 0°C, and coupled with a very low water activity, the enzymatic activity of the meat and of any bacteria therein effectively comes to a halt.

In trials conducted by the Applicant at -3°C the meat was kept for 50 days. The meat did not freeze but was pliable and did not require any defrosting before cooking. Such a method/process, highly advantageously, would appear to be far superior and more economical than simply freezing meat to -20°C to prolong shelf life. Using hurdle technology with a low water activity, - 3°C temperature and using antimicrobial methods of treatment as herein described would appear to overcome many disadvantages in freezing meat some of which are listed below.

Disadvantages of freezing meat:-

1 Energy is required to freeze meat to -20°C.

2 More energy is consumed during frozen storage to maintain a temperature of - 20°C.

3 More energy is required to defrost meat before the cooking process.

4 Time and manpower is required to defrost frozen meat.

5 Drip loss of 5% occurs when meat is defrosted.

6 Vitamins, flavonoids and proteins are lost in the drip loss, lowering its nutritional value. 7 Drip loss results in a dry and tasteless cooked food. When a piece of fresh chicken is cooked, it loses about 25% of its weight in the cooking. This loss is due to water expelled by the heat. For example, 200g of raw chicken when cooked, results in 150g of cooked meat. It has the same number of calories that raw meat had before.

When the antimicrobial method of the present invention (modified as explained employing the low temperature of -3C) is applied to raw chicken, 20% of the water content is removed. When the chicken is cooked, it only loses another 5%, thus net weight loss is 25%

When a frozen chicken is cooked, it loses a total of 30% weight. The extra 5% is the drip loss.

The advantage of the modified Applicant method/process with meat kept at -3 °C allows long term, cheaper storage of fresh raw chicken. It has the potential of being marketed anywhere in the world, shipped by sea, since it has a 50 days shelf life and also has higher nutritional values. The cooking time and energy required for cooking is reduced considerably also.

Shipping 1 ton of fresh meat at -3 °C is much cheaper than shipping 1 ton of frozen meat at - 20°C. In fact, the 1 ton frozen meat has 200 kg of pure frozen water, compared to meat produced by the modified process of the Applicant. The freight costs can be reduced by more than 20% when shipping the meat produced by the Applicant’s modified process Shipping a refrigerated container maintained at an internal temperature of -3 °C is much less expensive to run than a refrigerated container maintained at -20°C.

Therefore, further according to the present invention there is provided a an antimicrobial method of treatment of a raw meat product comprising one or more of the following features

1. Drying the meat before packaging,

2. Exposing the meat to dry chilled air in a temperature range of about 2 to 4 degrees Celsius

3. Exposing the meat to dry chilled air at a temperature below about 0 degrees Celsius and, preferably, at about -3 degrees (+/- 1 degree) Celsius

4. Maintaining the meat after packaging at a temperature above -20 degrees Celsius and, preferably, at about - 3 degrees (+/- 1 degree ) Celsius

5. Dehydrating the meat by 8 to 10 % and, preferably, by 10 to 12 %, and, preferably by about 20 % +/- 3 % 6. Extending the shelf life of a raw meat product beyond 5 days and preferably up to or beyond 14 days and preferably up to or beyond 50 days.

Furthermore, advantageously, methods according to the present invention can be subdivided into four stages or versions to deal with different food requirements;

The Primary Process

The Secondary Process

The Process for Ageing meat

The Process for Smoked meat & fish

The purpose of the Primary Process is to prolong the shelf life of fresh meat, by inhibiting bacterial and fungal growth on the surface or within the meat, during chilled storage. This is achieved by dehydrating meat by over 10% in weight. Consequently, the water activity is reduced in the meat, preventing bacterial and enzymatic activities. Thus, the shelflife e.g. for fresh poultry is increased from 5 days to 14 days with storage at 1°C to 2°C.

In the Secondary Process, the shelf life of fresh meat/ poultry is extended to over 50 days, while being stored at -3 °C, without the meat freezing. Advantageously, this is achieved by dehydrating meat by over 20% in weight. The resultant concentration of the proteins in the meat depresses the freezing point of the remaining water in the meat. Thus, meat can be stored at -3 °C without freezing. This lower temperature, coupled with low water activity, further reduces the enzymatic activities of the meat and bacteria to prolong the shelflife.

The Process for Ageing meat:-

The Ageing meat process of the present invention Process should not be confused with the dry Ageing meat process which is currently being used in the food industry. The two processes use different procedures with divergent aims.

In the traditional dry Ageing meat process, the purpose is to increase the “meaty” flavour and tenderise meat. This ageing process may also impart a “nutty” or “cheesey” flavour to the meat from the fungal and bacterial crust that grows on the meat’s surface. This outer contaminated crust is trimmed off to expose the edible meat. This trimming loss can be as high as 34%. The food industry has tried to reduce the trimming loss by using a wet ageing process and another process with moisture permeable bags, but, disadvantageously, the quality of the meat seems generally to be poor.

Advantageously, the Process for Ageing meat according to the present invention confers some of the qualities of dry ageing, e.g. increasing the “meaty” flavour, as removal of water from the meat tissues concentrates the flavour ingredients. The meat also tends to become tender during cold storage, as the natural enzymes continue, albeit at a much reduced rate, to break down complex proteins. Thus, this Process can be utilised to produce aged meat, by dehydration, in stepped down stages. This is achieved in a relatively short time, compared to traditional meat ageing. The process for this involves first removing 5% of the water via the Primary Process.

The second stage is leaving the meat to rest for a period of 24 hours under refrigeration at 2°C to 4°C. This step allows the migration of water in the meat tissues to equilibrate to the outer meat tissues. The third stage is removing a further 5 to 7% water with the Primary Process. The fourth step is allowing the meat to rest for another 24 hours. Steps 3 and 4 are repeated. The total average weight loss should be about 20%. The meat is now dry aged. It should now best be kept in cold storage at 2°C to 4°C.

The Applicant maintains that correct storage of fresh meat treated under the Processes in accordance with the present invention is important/vital in preserving the shelf life. All treated meat should preferably be vacuum packed in suitable packaging and kept at the temperatures specified;

For the Primary Process - at l°C to 2°C.

For the Secondary Process - at -3°C to -3.5°C.

For aged meat using the staged Process - at 2°C to 4°C.

In general, fresh meat, poultry and fish lose about 25% weight from evaporative loss of water during cooking (cooking loss). During the Primary Processing, the meat loses on average 10% of its original weight in dehydration. Upon cooking, the same meat further loses another 15%, making a total loss of 25%. This cooking loss is also the same for fresh, unprocessed meat. There is no disadvantage in using the Process in accordance with the present invention.. It is also notable, the time taken to cook this meat is generally 10% less. This clearly saves 10% of the cooking energy required as well. In the case of dry aged meat, the total weight loss from water is about 20%. When this meat is cooked, it loses about 5% in cooking loss. It also has a shorter cooking time and uses less cooking energy.

To summarise and elaborate:-

The Primary Process in accordance with the present invention is to extend the shelf life of fresh meat beyond 14 days.

An aim of the Primary Process is to extend the shelf life of fresh meat by inhibiting bacterial and fungal growth on the surface or within the meat, during chilled storage at 1 to 2°C. The shelf life increases from 5 to 14 days for fresh poultry. This is achieved by dehydrating fresh meat by 10 to 12% by weight, by using dry chilled air at 4°C.

Subsequently, the Secondary Process, can further extend the shelf life of fresh poultry to 50 days. In this process, the shelf life of fresh poultry is extended to over 50 days, while being stored at minus 3 °C, without the meat getting frozen. This is achieved by dehydrating meat by 20 to 22% by weight.

The resultant concentration of the proteins in the meat depresses the freezing point of the remaining water in the meat. Thus, meat can be stored at -3 °C without freezing. This lower temperature further reduces the enzymatic activities of the meat and bacteria to prolong the shelf life.

In one application of the the Secondary Process, the process starts with removal of all surface water by using air knives, stationed around all sides of the poultry pieces on the perforated, stainless steel conveyor. The temperature of the filtered air is ambient. The meat then is subjected to dry air, at a temperature of 2 to 4°C and at a dew point of about -15 to -70°C (preferably about -20°C). This process continues until the meat has lost about 5 to 7% weight. The meat is then stored at 2°C for 12 hours to allow the migration of water in the meat tissues to equilibrate to the outer meat tissues.

After this rest period, the meat is again subjected to more chilled air dehydration at 2 to 4°C and a dew point of about -15 to -70°C. Once the meat has lost another 5 to 7 percent weight, it is rested again at 2°C for 12 hours. The meat is again subjected to a final dehydration with chilled, dry air at -15 to -70°C dew point. The total weight loss from the start should be about 20 to 22%. The reason the weight loss of the water is done in stages is to prevent a dry, hard layer of crust forming on the surface, which would prevent dehydration of 20% in one step.

The meat is vacuum packed under waterproof packaging and stored at -3 to -3.5°C. Treated poultry meat does not get frozen at the above temperatures. The process described above was successfully applied to poultry, but can be applied to other meat.

Using the Process to dry age meat:-

Meat, e.g. beef is dry aged commercially to increase or concentrate its flavour and to tenderise the tougher muscle fibres and connective tissues. Technically, this is a controlled decomposition of meat. Traditionally this is achieved by holding meat at 4°C and at a relative humidity of 70% for a period of 30 days or more. During this process, the outer surface of the meat gets heavily encrusted with bacteria and mould. This is trimmed off before the meat is prepared for sale. Trimming loss can be as high as 34%.

The Process of the present invention confers the qualities of dry ageing of meat in a shorter period, e.g 14 days, compared to the traditional method of 30 days. This can help the processor double their production from their current processing unit. This would reduce cold storage costs too. With the Process of the present invention, there is no bacterial, or mould crust formed and therefore no trimming. The only intended loss is the moisture loss, resulting in the concentration of flavour. The Process applies forced, cold air, dehydration to the meat at staged intervals, keeping the process temperature at 2 to 4°C and at a dew point of -20 to -70°C. The Process starts with selected cuts of meat of similar size and weight. These are treated with jets of dry, filtered air at ambient temperature to blow off the surface moisture and juices. The meat is then subjected to dry, chilled air at a temperature of 2°C, at a dew point of -20 to -70°C. The Process is allowed to continue until there is an average loss of 5% of weight. The meat is stored at 2°C for 12 hours, at a dew point of -20°C.

The aforementioned Process step is again repeated for the second time until another weight loss of 5% occurs. The meat is again stored for 12 hours at a temperature of 2°C and a dew point of - 20°C to -70°C. The aforementioned Process step is repeated for the third time to lose another 5% weight. The total loss from the above stages is 15 to 18%.

The meat is then wrapped or packed in water proof packaging and stored at 2°C, for about 14 days to allow the natural enzymes to continue working slowly to tenderise the tough muscle fibres and connective tissues. After this period the meat is aged and ready for use.

The timings and temperatures mentioned above are approximate only. Different cuts of meat dictate different processing times dependent on fat content, size of bones in the cut and cattle breed, etc. Butchers experienced in the art of preparing cuts would be able to judge and select the appropriate timings for the Process.

Claims

1. An antimicrobial method of treatment of a raw food product such as beef or fish comprising exposing the surface of the raw food product rapidly to a high velocity flow of dry, chilled air sufficient to thereby dehydrate microorganisms on the raw product to a low enough level of water activity to prevent or restrain metabolic and replicating activity of the microorganisms, to thereby extend the shelf life of the raw product beyond a 5 day period.

2. A method as claimed in Claim 1 comprising an initial step of exposing the surface of said product to blown air at ambient temperature and at ambient relative humidity in order to remove most or nearly all (e.g. 99 %) of the free moisture and food product juices on said surface (preferably for about 40 +/- 10 seconds) prior to exposing the surface of the raw food product rapidly to a high velocity flow of dry, chilled air and, preferably, in which the surface of said product is exposed to blown air at ambient temperature for about 40 +/- 10 seconds.

3. A method as claimed in any one of the preceding claims in which the raw product is agitated or tumbled whilst being exposed to the air at ambient temperature and/or whilst being exposed to the high velocity flow of dry, chilled air and/or in which the product is suspended during treatment.

4. A method as claimed in any one of the preceding claims in which, after the raw product has been subjected to the high velocity flow of dry, chilled air, it is packed into waterproof packaging at a chilled temperature ready for cold storage.

5. A method as claimed in any one of the preceding claims in which a plurality of raw food products are treated substantially simultaneously or sequentially along a production line apparatus and/or including a misting/treatment of the product e.g with oil or sodium chloride.

6. A method as claimed in any one of the preceding claims in which the shelflife of the product is extended to up to 14 days and, preferably, including dehydrating the food product by about 8 to 12%.

7. A method as claimed in any one of the preceding claims including storing the food product at about 1 to 2° C.

8. A method as claimed in Claim 6 in which the shelf life of the product is extended up to or over 50 days.

9. A method as claimed in Claim 8 including dehydrating the food product by about 20 or 22%.

10. A method as claimed in Claim 9 in which the food product is exposed to a temperature of about -3° to -3.5°C and stored at this temperature.

11. A method as claimed in claim 9 applied to an aged beef product in which firstly 5 % of water is removed and the product is rested for about 24 hours under refrigeration at about 2 to 4°C after which a further 5 to 7% of water is removed with the product then being rested for about a further 24 hours after which a further 5 to 7°C of water is removed followed by a further rest period of about 24 hours yielding a total weight loss of about 20%, said aged beef now preferably being kept in storage at about 2 to 4 °C.

12. A method as claimed in Claim 10 applied to smoked fish in which the fish is dehydrated in a stream of air at a dew point of about -30°C and at a temperature of about 4°C for about 10 minutes preferably being allowed to rest for about 3 hours after which these steps are repeated four times to dehydrate the fish to 10% body weight, said fish preferably being smoked for about 12 hours to provide a total loss of body weight of 20%.

13. An antimicrobial method of treatment of a raw food product comprising one or more of the following features:-

1. Drying the product before packaging,

2. Exposing the product to dry chilled air in a temperature range of about 2 to 4 degrees Celsius

3. Exposing the product to dry chilled air at a temperature below about 0 degrees Celsius and, preferably, at about -3 degrees (+/- 1 degree) Celsius

4. Maintaining the product after packaging at a temperature above -20 degrees Celsius and, preferably, at about - 3 degrees (+/- 1 degree ) Celsius

5. Dehydrating the product by 8 to 10 % and, preferably, by 10 to 12 %, and, preferably by about 20 % +/- 3 %

6. Extending the shelf life of a raw food product beyond 5 days and preferably up to or beyond 14 days and preferably up to or beyond 50 days.

14. Apparatus for carrying out the method as described in any one of the preceding claims and, preferably, comprising means to deliver the high velocity flow of dry, chilled air in the form of air knives and, preferably, in which the air knives are positioned on either side of a conveyor means of the apparatus, in use, feeding raw food products sequentially past the air knives and, preferably, in which the conveyor means comprises a lower conveyor and/or an overhead conveyor and, preferably, including a (main) tunnel or enclosure in which raw food products are sequentially conveyed therethrough whilst being subjected to the high velocity flow of dry, chilled air.

15, Apparatus as claimed in claim 14 including means to deliver air at ambient temperature in the form of a second arrangement of air knives preferably suitably positioned on either side of the conveyor means of the apparatus and, preferably, including an auxiliary tunnel or enclosure in which raw food products can be sequentially conveyed therethrough (prior to treatment in the main tunnel) whilst being subjected to the air at ambient temperature and humidity, and/or including a packaging station for packing the raw food product/s after treatment..